[PyQt] PyQT UI freeze after long-run

[Robert Schilling]

I’ve written a PyQT application for doing automized measurements. 

The application layout is very simple:
The user interface lives in the main thread. There is a second thread (which is started by the main thread) for doing all the measurements.
This measurement-thread implements a state-machine and reports status to the user-interface using signals.

Now my problem:
This measurement is running about an hour. It continuously sends signals to the UI which prints them in a text field.
After a while the UI starts freezing (UI window title says it is that application is not responding) while the measurement is still ongoing. 
Then after a sudden all messages pops up in the UI again.

It seems that that the UI-main-thread doesn’t get any computation time.

Does anyone also encounter that problem? How to deal with it respectively how to debug it or find the error?

Thanks in advance!
Robert